My old reliable 2017 21" iMac has suddenly caught the kernel panic disease. This began the day before I upgraded to MacOS 12.4 and has continued. I have exhausted my resources in trying to figure out what's going on. I have taken the following steps:

• Removed peripherals including an external monitor/adapter and USB hub.
• Restarted in recovery mode to run Disk Utility on the boot drive and reinstall Monterey. DU reported no problems.
• Restarted in diagnostic mode. No problems reported.
• Totally uninstalled iStat Menus as that seemed a likely suspect. Kernel Panics continue.
• And, yes, I've looked at this: If Your Mac Restarts and a Message Appears

The kernel panics happen at very irregular and seemingly random times. In the middle of the night when I'm asleep. When I'm reading something on Safari. When I'm connected to a remote machine via an SSH tunnel. No consistency at all.

Looking at the panic reports </Library/Logs/DiagnosticReports/Retired/Kernel-2022-05-nn-nnnnn.panic> is remarkably unrevealing. The panicked thread/task named differs wildly and is often something like "kernel_task".

I can take it to a third party repair place and hope for the best. Or I can take it to an Apple contracted repair service provider. But, either way, what can they do to figure out what's wrong?

I'm thinking it's a lost cause.

Other opinions?

Rule out Monterey 12.3+. Format an external with something that was working fine BEFORE 12.3 and use it for a while. If you still see random kernel panics that way, you can probably start assuming hardware something.

A fresh install of macOS < Monterey (whatever you were using before 12.3 that did NOT do this) might shine the light on 12.3 and 12.4 instead of other possibilities like some hardware conking out on you. IMO, Monterey is still pretty buggy- I have lots of issues with the jacks on a brand new Mac Ultra- even the ethernet jack. Very stable RAID drive is fine on Macs running < Monterey macOS but won't stay connected for more than a few hours when connected to a Monterey Mac. Etc. Thus, if me, I'd first rule out Monterey as the cause.

Anything else changed around the time this started happening? New hardware? Hub? Etc. If you can recall any other possible catalysts like that- even remote possibilities- get them back OUT of the setup while you run this pre-Monterey test. I just had a bizarre problem causing hard crashes when selecting Airply to only Sonos speakers (other stuff worked normally). Airplay to Sonos has worked fine before 12.4 upgrade too. Through much trial & error, I finally got the idea to try unhooking from Ethernet and try wifi. Airplay to Sonos worked fine again. Turned off wifi and hooked the same Ethernet cable back in. Airplay to Sonos worked fine again.

I miss "just works" Apple. But in the meantime, scrutinize everything. It very well could be 12.3 and 4 instead of aging hardware or third party software.

I hadn't changed anything recently either hardware or new software. (Lots of software updates, though.) External monitor and adapter have been there six months. USB hub is a couple of years old. Most recent hard drive addition was a couple of years ago. I did change routers several months ago and there is a CAT 5 cable between router and iMac. Maybe I'll disconnect the ethernet and just stick to WiFi a while.

It seems a bit crazy that this sort of thing is so hard to track down and that Apple doesn't really supply any tools to help.

One possible hint, both of this morning's kernel panics happened when I was filling out response fields in online forums with Safari. Once here and once on a garden pond forum. As I recall, this has happened a couple of times in the past few weeks. On the other hand, some of the panics happened when I was asleep or otherwise away from the machine and not doing anything.